linux.git/kernel/trace/trace_preemptirq.c, branch v7.0 Linux kernel source tree tracing: Fix archs that still call tracepoints without RCU watching 2024-12-05T14:28:58+00:00 Steven Rostedt rostedt@goodmis.org 2024-12-04T15:04:14+00:00 dc1b157b828dfe412c776ac1dd8db158f6016b39 Tracepoints require having RCU "watching" as it uses RCU to do updates to the tracepoints. There are some cases that would call a tracepoint when RCU was not "watching". This was usually in the idle path where RCU has "shutdown". For the few locations that had tracepoints without RCU watching, there was an trace_*_rcuidle() variant that could be used. This used SRCU for protection. There are tracepoints that trace when interrupts and preemption are enabled and disabled. In some architectures, these tracepoints are called in a path where RCU is not watching. When x86 and arm64 removed these locations, it was incorrectly assumed that it would be safe to remove the trace_*_rcuidle() variant and also remove the SRCU logic, as it made the code more complex and harder to implement new tracepoint features (like faultable tracepoints and tracepoints in rust). Instead of bringing back the trace_*_rcuidle(), as it will not be trivial to do as new code has already been added depending on its removal, add a workaround to the one file that still requires it (trace_preemptirq.c). If the architecture does not define CONFIG_ARCH_WANTS_NO_INSTR, then check if the code is in the idle path, and if so, call ct_irq_enter/exit() which will enable RCU around the tracepoint. Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Mark Rutland <mark.rutland@arm.com> Link: https://lore.kernel.org/20241204100414.4d3e06d0@gandalf.local.home Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> Fixes: 48bcda684823 ("tracing: Remove definition of trace_*_rcuidle()") Closes: https://lore.kernel.org/all/bddb02de-957a-4df5-8e77-829f55728ea2@roeck-us.net/ Acked-by: Paul E. McKenney <paulmck@kernel.org> Tested-by: Guenter Roeck <linux@roeck-us.net> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Tested-by: Madhavan Srinivasan <maddy@linux.ibm.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> 
Tracepoints require having RCU "watching" as it uses RCU to do updates to
the tracepoints. There are some cases that would call a tracepoint when
RCU was not "watching". This was usually in the idle path where RCU has
"shutdown". For the few locations that had tracepoints without RCU
watching, there was an trace_*_rcuidle() variant that could be used. This
used SRCU for protection.

There are tracepoints that trace when interrupts and preemption are
enabled and disabled. In some architectures, these tracepoints are called
in a path where RCU is not watching. When x86 and arm64 removed these
locations, it was incorrectly assumed that it would be safe to remove the
trace_*_rcuidle() variant and also remove the SRCU logic, as it made the
code more complex and harder to implement new tracepoint features (like
faultable tracepoints and tracepoints in rust).

Instead of bringing back the trace_*_rcuidle(), as it will not be trivial
to do as new code has already been added depending on its removal, add a
workaround to the one file that still requires it (trace_preemptirq.c). If
the architecture does not define CONFIG_ARCH_WANTS_NO_INSTR, then check if
the code is in the idle path, and if so, call ct_irq_enter/exit() which
will enable RCU around the tracepoint.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/20241204100414.4d3e06d0@gandalf.local.home
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Fixes: 48bcda684823 ("tracing: Remove definition of trace_*_rcuidle()")
Closes: https://lore.kernel.org/all/bddb02de-957a-4df5-8e77-829f55728ea2@roeck-us.net/
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
tracing: Remove definition of trace_*_rcuidle() 2024-10-09T01:17:39+00:00 Steven Rostedt rostedt@goodmis.org 2024-10-03T22:16:29+00:00 48bcda6848232667f13b4e97588de488c83c37d4 The trace_*_rcuidle() variant of a tracepoint was to handle places where a tracepoint was located but RCU was not "watching". All those locations have been removed, and RCU should be watching where all tracepoints are located. We can now remove the trace_*_rcuidle() variant. Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Joel Fernandes <joel@joelfernandes.org> Link: https://lore.kernel.org/20241003181629.36209057@gandalf.local.home Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> 
The trace_*_rcuidle() variant of a tracepoint was to handle places where a
tracepoint was located but RCU was not "watching". All those locations
have been removed, and RCU should be watching where all tracepoints are
located. We can now remove the trace_*_rcuidle() variant.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Link: https://lore.kernel.org/20241003181629.36209057@gandalf.local.home
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
cpuidle: tracing, preempt: Squash _rcuidle tracing 2023-01-31T14:01:46+00:00 Peter Zijlstra peterz@infradead.org 2023-01-31T08:50:36+00:00 3017ba4b831bc7fd67cc82e744116b6e45e259a4 Extend/fix commit: 9aedeaed6fc6 ("tracing, hardirq: No moar _rcuidle() tracing") ... to also cover trace_preempt_{on,off}() which were mysteriously untouched. Fixes: 9aedeaed6fc6 ("tracing, hardirq: No moar _rcuidle() tracing") Reported-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Mark Rutland <mark.rutland@arm.com> Link: https://lkml.kernel.org/r/Y9D5AfnOukWNOZ5q@hirez.programming.kicks-ass.net Link: https://lore.kernel.org/r/Y9jWXKgkxY5EZVwW@hirez.programming.kicks-ass.net 
Extend/fix commit:

  9aedeaed6fc6 ("tracing, hardirq: No moar _rcuidle() tracing")

... to also cover trace_preempt_{on,off}() which were mysteriously
untouched.

Fixes: 9aedeaed6fc6 ("tracing, hardirq: No moar _rcuidle() tracing")
Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lkml.kernel.org/r/Y9D5AfnOukWNOZ5q@hirez.programming.kicks-ass.net
Link: https://lore.kernel.org/r/Y9jWXKgkxY5EZVwW@hirez.programming.kicks-ass.net
tracing, hardirq: No moar _rcuidle() tracing 2023-01-13T10:48:16+00:00 Peter Zijlstra peterz@infradead.org 2023-01-12T19:43:49+00:00 9aedeaed6fc6fe8452b9b8225e95cc2b8631ff91 Robot reported that trace_hardirqs_{on,off}() tickle the forbidden _rcuidle() tracepoint through local_irq_{en,dis}able(). For 'sane' configs, these calls will only happen with RCU enabled and as such can use the regular tracepoint. This also means it's possible to trace them from NMI context again. Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20230112195541.477416709@infradead.org 
Robot reported that trace_hardirqs_{on,off}() tickle the forbidden
_rcuidle() tracepoint through local_irq_{en,dis}able().

For 'sane' configs, these calls will only happen with RCU enabled and
as such can use the regular tracepoint. This also means it's possible
to trace them from NMI context again.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230112195541.477416709@infradead.org
tracing: Remove trace_hardirqs_{on,off}_caller() 2023-01-13T10:48:16+00:00 Peter Zijlstra peterz@infradead.org 2023-01-12T19:43:47+00:00 dc7305606d480f34d9ed960fcaceac81d0f38436 Per commit 56e62a737028 ("s390: convert to generic entry") the last and only callers of trace_hardirqs_{on,off}_caller() went away, clean up. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20230112195541.355283994@infradead.org 
Per commit 56e62a737028 ("s390: convert to generic entry") the last
and only callers of trace_hardirqs_{on,off}_caller() went away, clean
up.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230112195541.355283994@infradead.org
tracing: hold caller_addr to hardirq_{enable,disable}_ip 2022-09-07T02:26:00+00:00 Yipeng Zou zouyipeng@huawei.com 2022-09-01T10:45:14+00:00 54c3931957f6a6194d5972eccc36d052964b2abe Currently, The arguments passing to lockdep_hardirqs_{on,off} was fixed in CALLER_ADDR0. The function trace_hardirqs_on_caller should have been intended to use caller_addr to represent the address that caller wants to be traced. For example, lockdep log in riscv showing the last {enabled,disabled} at __trace_hardirqs_{on,off} all the time(if called by): [ 57.853175] hardirqs last enabled at (2519): __trace_hardirqs_on+0xc/0x14 [ 57.853848] hardirqs last disabled at (2520): __trace_hardirqs_off+0xc/0x14 After use trace_hardirqs_xx_caller, we can get more effective information: [ 53.781428] hardirqs last enabled at (2595): restore_all+0xe/0x66 [ 53.782185] hardirqs last disabled at (2596): ret_from_exception+0xa/0x10 Link: https://lkml.kernel.org/r/20220901104515.135162-2-zouyipeng@huawei.com Cc: stable@vger.kernel.org Fixes: c3bc8fd637a96 ("tracing: Centralize preemptirq tracepoints and unify their usage") Signed-off-by: Yipeng Zou <zouyipeng@huawei.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> 
Currently, The arguments passing to lockdep_hardirqs_{on,off} was fixed
in CALLER_ADDR0.
The function trace_hardirqs_on_caller should have been intended to use
caller_addr to represent the address that caller wants to be traced.

For example, lockdep log in riscv showing the last {enabled,disabled} at
__trace_hardirqs_{on,off} all the time(if called by):
[   57.853175] hardirqs last  enabled at (2519): __trace_hardirqs_on+0xc/0x14
[   57.853848] hardirqs last disabled at (2520): __trace_hardirqs_off+0xc/0x14

After use trace_hardirqs_xx_caller, we can get more effective information:
[   53.781428] hardirqs last  enabled at (2595): restore_all+0xe/0x66
[   53.782185] hardirqs last disabled at (2596): ret_from_exception+0xa/0x10

Link: https://lkml.kernel.org/r/20220901104515.135162-2-zouyipeng@huawei.com

Cc: stable@vger.kernel.org
Fixes: c3bc8fd637a96 ("tracing: Centralize preemptirq tracepoints and unify their usage")
Signed-off-by: Yipeng Zou <zouyipeng@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
lockdep: Fix -Wunused-parameter for _THIS_IP_ 2022-04-05T08:24:34+00:00 Nick Desaulniers ndesaulniers@google.com 2022-03-14T22:19:03+00:00 8b023accc8df70e72f7704d29fead7ca914d6837 While looking into a bug related to the compiler's handling of addresses of labels, I noticed some uses of _THIS_IP_ seemed unused in lockdep. Drive by cleanup. -Wunused-parameter: kernel/locking/lockdep.c:1383:22: warning: unused parameter 'ip' kernel/locking/lockdep.c:4246:48: warning: unused parameter 'ip' kernel/locking/lockdep.c:4844:19: warning: unused parameter 'ip' Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Link: https://lore.kernel.org/r/20220314221909.2027027-1-ndesaulniers@google.com 
While looking into a bug related to the compiler's handling of addresses
of labels, I noticed some uses of _THIS_IP_ seemed unused in lockdep.
Drive by cleanup.

-Wunused-parameter:
kernel/locking/lockdep.c:1383:22: warning: unused parameter 'ip'
kernel/locking/lockdep.c:4246:48: warning: unused parameter 'ip'
kernel/locking/lockdep.c:4844:19: warning: unused parameter 'ip'

Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Waiman Long <longman@redhat.com>
Link: https://lore.kernel.org/r/20220314221909.2027027-1-ndesaulniers@google.com
lockdep: fix order in trace_hardirqs_off_caller() 2020-09-14T08:08:07+00:00 Sven Schnelle svens@linux.ibm.com 2020-09-10T10:24:53+00:00 73ac74c7d489756d2313219a108809921dbfaea1 Switch order so that locking state is consistent even if the IRQ tracer calls into lockdep again. Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> 
Switch order so that locking state is consistent even
if the IRQ tracer calls into lockdep again.

Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
x86/entry: Rename trace_hardirqs_off_prepare() 2020-06-11T13:15:24+00:00 Peter Zijlstra peterz@infradead.org 2020-05-29T21:27:40+00:00 bf2b3008440072068580c609d79a079656af0588 The typical pattern for trace_hardirqs_off_prepare() is: ENTRY lockdep_hardirqs_off(); // because hardware ... do entry magic instrumentation_begin(); trace_hardirqs_off_prepare(); ... do actual work trace_hardirqs_on_prepare(); lockdep_hardirqs_on_prepare(); instrumentation_end(); ... do exit magic lockdep_hardirqs_on(); which shows that it's named wrong, rename it to trace_hardirqs_off_finish(), as it concludes the hardirq_off transition. Also, given that the above is the only correct order, make the traditional all-in-one trace_hardirqs_off() follow suit. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20200529213321.415774872@infradead.org 
The typical pattern for trace_hardirqs_off_prepare() is:

  ENTRY
    lockdep_hardirqs_off(); // because hardware
    ... do entry magic
    instrumentation_begin();
    trace_hardirqs_off_prepare();
    ... do actual work
    trace_hardirqs_on_prepare();
    lockdep_hardirqs_on_prepare();
    instrumentation_end();
    ... do exit magic
    lockdep_hardirqs_on();

which shows that it's named wrong, rename it to
trace_hardirqs_off_finish(), as it concludes the hardirq_off transition.

Also, given that the above is the only correct order, make the traditional
all-in-one trace_hardirqs_off() follow suit.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200529213321.415774872@infradead.org
lockdep: Prepare for noinstr sections 2020-05-19T13:47:21+00:00 Peter Zijlstra peterz@infradead.org 2020-03-18T13:22:03+00:00 c86e9b987cea3dd0209203e714553a47f5d7c6dd Force inlining and prevent instrumentation of all sorts by marking the functions which are invoked from low level entry code with 'noinstr'. Split the irqflags tracking into two parts. One which does the heavy lifting while RCU is watching and the final one which can be invoked after RCU is turned off. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Link: https://lkml.kernel.org/r/20200505134100.484532537@linutronix.de 
Force inlining and prevent instrumentation of all sorts by marking the
functions which are invoked from low level entry code with 'noinstr'.

Split the irqflags tracking into two parts. One which does the heavy
lifting while RCU is watching and the final one which can be invoked after
RCU is turned off.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Link: https://lkml.kernel.org/r/20200505134100.484532537@linutronix.de